This application relates to a cooling structure wherein electrodes are placed in on one end of a cooling tube, to provide a restriction preventing backflow of a vapor from a dielectric liquid moving in a non-desired direction.
The thermal management of electronics presents a large and growing challenge. High power density electronics require an increase in the heat flux generated by electronic devices, such that passive cooling may no longer be sufficient. Thermal management limitations are beginning to present a ceiling from electronics reaching full capacity.
As an example, clock speeds on central processing units have been reduced, and the power rating for power electronic components has been restricted. The theoretical operating limits of the electronic devices far exceed what is possible to implement with present cooling solutions.
Fluid pumping has been proposed, however, most mechanical pumps raise reliability issues, and can introduce noise, vibration and other challenges.
Dielectrophoretic pumping is known, and has been proposed for some applications in cooling electronics. A dielectrophoretic force is generally provided by varying an electrical response relative to a bubble which is formed in a dielectric fluid. In general, the dielectric liquid behaves in one way relative to a dielectrophoretic force, but a bubble of vapor will react in a distinct manner.
One challenge in utilizing two-phase cooling occurs when very small cooling channels are utilized. Such channels, known as microchannels, face challenges when a bubble forms within the fluid. The bubbles expand in both an upstream and downstream direction, and radially outwardly. Expansion in the upstream direction is undesirable, and may cause excessive pressure oscillations and can introduce vapor to an inlet plenum, which can in turn cause flow mal-distribution.
A physical restriction to inhibit this growth would increase the pressure drop on the channel, which is also undesirable.